The usual way to diagnose small-bowel perforation is by demonstration of
free intraperitoneal air on plain abdominal or erect chest
radiographs1.
Contrast examination of the small bowel is seldom performed in acute
cases.

CASE HISTORY

A man aged 72 underwent total colectomy for uncontrol-lable ulcerative
colitis. Postoperatively he developed subhepatic collections diagnosed by
abdominal ultrasound examination, probably secondary to perforation of a
duodenal ulcer. At that time the patient was too frail to undergo repeat
laparotomy and a conservative management strategy was chosen. A Robinson drain
was inserted under ultrasound guidance that initially drained offensive
purulent fluid but after two days began to drain up to 2 litres per day of
what appeared to be small-bowel contents. A Gastrografin follow-through
examination did not reveal leakage from the small bowel
(Figure 1). Drainage continued
unabated overnight and clinically small-bowel perforation still seemed likely.
The next morning, 18 hours after the follow-through investigation, a specimen
of drain fluid was X-rayed against a control specimen of water and was seen to
contain contrast agent (Figure
2). This was confirmed by densitometry—drain contents 0.81,
water 0.45. A sinogram (Figure
3) then showed that the drain lay within the jejunum. The drain
was removed and the patient recovered uneventfully.

COMMENT

In a prospective series of 1000 consecutive patients having combined upper
gastrointestinal and small-bowel studies only 14% were performed to exclude
perforation2. The
technique is best suited to disorders presenting non-acutely, for example
Crohn's disease, neoplasms, radiation enteritis, or
tuberculosis1. It
was chosen in this patient because the presence of free air on plain
radiography was thought to be an unreliable indicator after laparotomy and
drain insertion, and diagnostic laparotomy would not have been tolerated.

Why was the small-bowel perforation missed in the Gastrografin
follow-through? The use of barium as a contrast agent is absolutely
contraindicated when bowel perforation is
suspected1.
Gastrografin was chosen because it is
water-soluble3.
There are no published data to suggest that the choice of contrast agent
influences interpretation of single-contrast small-bowel studies. Maglinte,
Burney and Miller reviewed 42 small-bowel lesions missed on follow-through
examination but were later demonstrated by enteroclysis (small-bowel enema)
and at operation4.
Most of the lesions had been missed because of technical inadequacies with the
follow-through, although none of the missed lesions were perforations.
Buckwalter and Herbst addressed the means of diagnosis of bowel leak in 791
patients who had undergone gastric bariatric surgery. Of the 19 patients who
developed leaks, only 7 were diagnosed by Gastrografin swallow, the remainder
being identified clinically or by oral dye studies, barium swallow, sinogram
or at laparotomy5.
The authors do not say whether enteroclysis was used in their institution at
that time.

Enteroclysis is a reliable, accurate, quick means of imaging the small
bowel. It is more invasive than follow-through but the radiation dose is
lower6. Usually it
is performed as an elective procedure on prepared bowel. Whether enteroclysis
would have detected the migration of the intraperitoneal drain in our patient
is debatable.

Finally, would a sinogram have been a more appropriate initial
investigation? Without the information from the radiograph of the drain
specimens, we believe that a sinogram would have been contraindicated in these
circumstances. There is a risk of delivering contrast agent to the peritoneum,
with only a small chance of making the diagnosis.

In this case, radiography of drain contents established the diagnosis of
small-bowel perforation without further irradiation or invasive procedures. We
have not found any previous report of such a technique.